Clean production system of 4, 6-dihydroxypyrimidine

Abstract

The utility model discloses a clean production system of 4, 6-dihydroxypyrimidine, which comprises a sodium methoxide methanol concentration kettle, a reaction kettle and a crystallization kettle, a sodium methoxide methanol solution adding pipeline and a condenser pipe are arranged on the sodium methoxide methanol concentration kettle, an outlet of the condenser pipe is connected with a methanol recovery tank, and the methanol recovery tank is connected with the reaction kettle. A discharging pipeline of the sodium methoxide methanol concentration kettle is connected with a feeding pipeline of the reaction kettle, and a liquid material adding pipeline is divided into a plurality of branch pipes which are respectively connected with a dimethyl malonate feeding pipe, a formamide feeding pipe, a methanol feeding pipe, a stabilizer adding pipe, an organic filtrate feeding pipe and a hydrochloric acid methanol solution feeding pipe; a discharging pipeline of the reaction kettle is connected with the first centrifugal machine. The method not only improves the product yield, effectively realizes resource application and recycling, but also effectively reduces the organic matter content of the wastewater and the waste salt, thereby reducing the treatment cost, being friendly to the environment and having higher economic and social benefits.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical production, in particular to a clean production system for 4,6-dihydroxypyrimidine. Background Art

[0002] 4,6-Dihydroxypyrimidine is generally used as an intermediate in organic synthesis and is used to produce sulfonamide drug sulfamoxine in the pharmaceutical industry. 4,6-Dihydroxypyrimidine is also an intermediate for vitamin B4, anti-tumor drugs and adjuvant drugs (RTFCS#UW7523000), and it can be further made into dichloropyrimidine, which is a new type of highly active fungicide with a wide application market.

[0003] The current industrial production method of 4,6-dihydroxypyrimidine is to directly cyclize dimethyl malonate and formamide under the condition of sodium methoxide to generate pyrimidine sodium salt, and then acidify with hydrochloric acid to obtain the target product 4,6-dihydroxypyrimidine. For every ton of 4,6-dihydroxypyrimidine produced, there are approximately 10 tons of acidified wastewater. The acidified wastewater cannot be effectively recycled and can only be discharged after environmental protection treatment, so the treatment cost is very high.

[0004] The current industrial production process has the following problems: (1) In the amination cyclization reaction, due to the properties of the materials, the cyclization reaction is incomplete, and side reactions occur to generate more impurities, resulting in a decrease in the yield. (2) The recovered formic acid and water have similar boiling points and cannot be effectively separated and recycled. (3) There are a large number of organic substances in the wastewater, which is difficult to treat and leads to a high treatment cost. (4) The solubility of 4,6-dihydroxypyrimidine in the acidified wastewater is about 0.2%, which means that 20KG of products will be lost for every ton of products produced, and the production cost will increase. Summary of the Utility Model

[0005] To solve the above technical problems, the utility model provides a clean production system for 4,6-dihydroxypyrimidine, achieving the effects of more complete cyclization reaction, higher yield, high purity and low cost of recovered formic acid, reduced organic matter content in wastewater and reduced treatment cost, and finally realizing the purpose of efficient resource utilization, energy conservation and emission reduction, reducing environmental protection risks and greatly improving economic benefits.

[0006] To achieve the above object, the utility model realizes the above object through the following technical solutions: A clean production system for 4,6-dihydroxypyrimidine, comprising a sodium methoxide methanol concentration kettle, a reaction kettle and a crystallization kettle, characterized in that: a sodium methoxide methanol solution adding pipeline and a condenser are arranged on the sodium methoxide methanol concentration kettle, the outlet of the condenser is connected to a methanol recovery tank, the discharging pipeline of the sodium methoxide methanol concentration kettle is connected to the feeding pipeline of the reaction kettle, a solid material adding port and a liquid material adding pipeline are further arranged on the reaction kettle, a heating jacket is arranged outside the reaction kettle, the liquid material adding pipeline is branched into multiple branch pipes respectively connected to a dimethyl malonate feeding pipe, a formamide feeding pipe, a methanol feeding pipe, a stabilizer adding pipe, an organic filtrate feeding pipe and a hydrochloric acid methanol solution feeding pipe, the discharging pipeline of the reaction kettle is connected to a first centrifuge, the filtrate pipeline of the first centrifuge is connected to an organic filtrate storage tank, the organic filtrate storage tank is connected to the organic filtrate feeding pipe, and the methanol recovery tank is connected to the methanol feeding pipe;

[0007] The solid material of the first centrifuge enters the crystallization kettle, a water adding pipe, a sodium carbonate solution adding pipe, a hydrochloric acid solution feeding pipe and a first filtrate feeding pipe are connected to the crystallization kettle, the discharging pipeline of the crystallization kettle is connected to a second centrifuge, the filtrate outlet pipeline of the second centrifuge is connected to a first filtrate storage tank, and the first filtrate storage tank is connected to the first filtrate feeding pipe;

[0008] The solid material of the second centrifuge enters the purification kettle, a purification hydrochloric acid solution feeding pipe and a second filtrate feeding pipe are connected to the purification kettle, the discharging pipe of the purification kettle is connected to a third centrifuge, the filtrate outlet of the third centrifuge is connected to a second filtrate storage tank, and the second filtrate storage tank is connected to the second filtrate feeding pipe.

[0009] In the above solution: the sodium methoxide methanol solution adding pipeline is connected to a sodium methoxide methanol solution storage tank, and a nitrogen pipeline is connected to the sodium methoxide methanol concentration kettle. The concentrated sodium methoxide methanol is pressed into the reaction kettle by nitrogen.

[0010] In the above solution: a nitrogen pipeline is arranged on the reaction kettle, metering pumps are respectively arranged on the dimethyl malonate feeding pipe, the formamide feeding pipe, the methanol feeding pipe, the stabilizer adding pipe, the organic filtrate feeding pipe and the hydrochloric acid methanol solution feeding pipe, the dimethyl malonate feeding pipe and the formamide feeding pipe are respectively connected to a dimethyl malonate storage tank and a formamide storage tank, the stabilizer adding pipe is connected to a stabilizer storage tank, and the hydrochloric acid methanol solution is connected to a hydrochloric acid methanol solution storage tank.

[0011] In the above solution: nitrogen pipelines are also provided on the crystallization kettle and the purification kettle, nitrogen valves are provided on all the nitrogen pipelines, metering pumps are respectively provided on the sodium carbonate solution addition pipe, the hydrochloric acid solution feeding pipe and the first filtrate feeding pipe, and the sodium carbonate solution addition pipe and the hydrochloric acid solution feeding pipe are respectively connected to the sodium carbonate solution storage tank and the hydrochloric acid solution storage tank;

[0012] Metering pumps are also provided on the purified hydrochloric acid solution feeding pipe and the second filtrate feeding pipe, and the purified hydrochloric acid solution feeding pipe is connected to the purified hydrochloric acid solution storage tank. The materials in the crystallization kettle and the purification kettle are pressed out by nitrogen.

[0013] In the above solution: the organic filtrate storage tank is also connected to the inlet pipeline of the fractionating column through a pipeline, the stabilizer outlet pipeline of the fractionating column is connected to the stabilizer recovery storage tank, and the methanol outlet pipeline of the fractionating column is connected to the methanol recovery tank.

[0014] In the above solution: the bottom residue outlet pipeline of the fractionating column is connected to the incinerator.

[0015] In the above solution: a stirring device is provided inside the reaction kettle.

[0016] First, the prepared sodium methoxide methanol solution is placed in the sodium methoxide methanol solution storage tank and pumped into the sodium methoxide methanol concentration kettle through a metering pump. The sodium methoxide methanol concentration kettle is heated and concentrated, and methanol is distilled out. The distilled methanol vapor is condensed through a condenser pipe and then collected into the methanol recovery tank. The concentrated sodium methoxide methanol solution is pressed into the reaction kettle by nitrogen, and then dimethyl malonate, formamide, and stabilizers (such as ethyl acetate and methyl formate) are pumped in through a metering pump. A catalyst (such as quaternary ammonium bases like tetramethylammonium hydroxide, tetramethylammonium bicarbonate, and tetraethylammonium hydroxide) is added through the solid material addition port. A stirring device is provided inside the reaction kettle, and the reaction is carried out by heating. After the reaction is completed, it is cooled, and then methanol in the methanol recovery tank or the organic filtrate in the organic filtrate storage tank is added through a metering pump and stirred to disperse into a suspension. Then, hydrochloric acid methanol solution is added to the reaction kettle through a metering pump for acidification to slightly acidic, and the materials are pressed into the first centrifuge by nitrogen for centrifugal filtration to separate the organic filtrate into the organic filtrate storage tank.

[0017] The solid mixture of 4,6-dihydroxypyrimidine disodium salt and sodium chloride is transferred into the crystallization kettle, washed with water through the water addition pipe, and then sodium carbonate solution is added through a metering pump until it is slightly alkaline to dissolve the solid, obtaining a mixed sodium salt solution.

[0018] Then, hydrochloric acid solution and the recycled first filtrate are added through a metering pump for acidification crystallization. The crystallization materials are pressed into the second centrifuge by nitrogen for centrifugal filtration to obtain the crude product of 4,6-dihydroxypyrimidine. The filtrate of the second centrifuge enters the first filtrate storage tank for recycling.

[0019] 4,6-Dihydroxypyrimidine crude product is put into the purification kettle, and purified by adding purified hydrochloric acid solution or the recycled second filtrate. Then, it is sent into the third centrifuge through nitrogen, and centrifuged. A water pipe is connected to the third centrifuge, and after centrifugation, the solid is rinsed with water. After drying, 4,6-dihydroxypyrimidine product is obtained.

[0020] The separated organic filtrate is recycled and reused multiple times. When the formic acid content in the filtrate reaches a certain concentration, it is added to the fractionating column for fractional distillation to recover methanol and stabilizer. The stabilizer is recycled. Methanol is collected in the methanol recovery tank. The bottom residue of the fractionating column enters the incinerator for incineration to burn the residual organic matter, obtaining solid sodium salt containing impurities. The solid sodium salt containing impurities is dissolved with the first filtrate, separated and filtered. The carbon residue is treated as waste residue, and the filtrate is evaporated to recover water and recycled to the system for reuse. Evaporation and crystallization yield by-product sodium chloride.

[0021] Beneficial effects;

[0022] (1) Adding a catalyst can increase the alkalinity of the sodium methoxide methanol solution and accelerate the reaction between malonic ester and formamide; adding a stabilizer can improve the properties of the reaction materials, making the amidation cyclization reaction more complete and increasing the product conversion rate.

[0023] (2) Using and recycling the hydrochloric acid methanol solution can disperse 4,6-dihydroxypyrimidine disodium salt and organic matter, efficiently recover recycled organic matters such as methanol, formic acid and stabilizer, and achieve resource-based recycling utilization.

[0024] (3) Incinerating the residual organic matter after fractional distillation can effectively reduce the organic matter in the wastewater and the difficulty of wastewater treatment.

[0025] (4) Recycling the filtrate for secondary purification to remove salt can reduce the consumption of hydrochloric acid, effectively reduce the product loss in acidified water, and increase the product yield.

[0026] By designing a method for synthesizing 4,6-dihydroxypyrimidine and a clean process route for its efficient resource-based utilization, the present utility model not only increases the product yield, effectively realizes resource-based recycling and reuse, but also effectively reduces the organic matter content in wastewater and waste salt, thereby reducing the treatment cost, being environmentally friendly, and having higher economic and social benefits. Description of the Drawings

[0027] Figure 1 It is the process flow diagram of the present utility model. Detailed Embodiments

[0028] The following further describes the present utility model in conjunction with the drawings and embodiments.

[0029] Example 1

[0030] As Figure 1As shown, the clean production system of 4,6-dihydroxypyrimidine of the utility model comprises a sodium methoxide methanol concentration kettle 1, a reaction kettle 2, a crystallization kettle 3 and a purification kettle 4.

[0031] The sodium methoxide methanol concentration kettle 1 is provided with a sodium methoxide methanol solution adding pipeline and a condenser 5, the outlet of the condenser 5 is connected to the methanol recovery tank 6, the condenser 5 is water-cooled, the water inlet and outlet are respectively connected to the condensed water circulation system, a stirring device is provided in the sodium methoxide methanol concentration kettle 1, and a heating jacket is provided outside the sodium methoxide methanol concentration kettle 1, which is a conventional design. The sodium methoxide methanol solution adding pipeline is connected to the sodium methoxide methanol solution storage tank 7 through a metering pump, and the sodium methoxide methanol concentration kettle 1 is connected with a nitrogen pipeline 8. A nitrogen valve 9 is provided on the nitrogen pipeline 8.

[0032] The discharge pipeline of the sodium methoxide methanol concentration kettle is connected to the feed pipeline of the reactor 2. The reactor is also provided with a solid material addition port and a liquid material addition pipeline. A heating jacket is provided outside the reactor. A stirring device is provided inside the reactor 2. A nitrogen pipeline 8 is provided on the reactor 2. A nitrogen valve 9 is provided on the nitrogen pipeline 8. The liquid material adding pipeline is divided into a plurality of branch pipes which are respectively connected to the dimethyl malonate feeding pipe, the formamide feeding pipe, the methanol feeding pipe, the stabilizer adding pipe, the organic filtrate feeding pipe and the hydrochloric acid methanol solution feeding pipe. The dimethyl malonate feeding pipe, the formamide feeding pipe, the methanol feeding pipe, the stabilizer adding pipe, the organic filtrate feeding pipe and the hydrochloric acid methanol solution feeding pipe are respectively provided with metering pumps. The dimethyl malonate feeding pipe and the formamide feeding pipe are respectively connected to the dimethyl malonate storage tank 10 and the formamide storage tank 11. The stabilizer adding pipe is connected to the stabilizer storage tank 12. The hydrochloric acid methanol solution is connected to the hydrochloric acid methanol solution storage tank 13.

[0033] The discharge pipeline of the reactor 1 is connected to the first centrifuge 14, the filtrate pipeline of the first centrifuge 14 is connected to the organic filtrate storage tank 15, the organic filtrate storage tank 15 is connected to the organic filtrate feeding pipe through a metering pump, and the methanol recovery tank 6 is connected to the methanol feeding pipe through a metering pump.

[0034] The solid material of the first centrifuge 14 enters the crystallization kettle 3, which is connected with a water adding pipe, a sodium carbonate solution adding pipe, a hydrochloric acid solution feeding pipe and a first filtrate feeding pipe, and the discharge pipeline of the crystallization kettle is connected with the second centrifuge 17, and the filtrate outlet pipeline of the second centrifuge 17 is connected with the first filtrate storage tank 18, and the first filtrate feeding pipe is connected with the first filtrate storage tank 18. The crystallization kettle 3 and the purification kettle 4 are also provided with nitrogen pipelines, and all nitrogen pipelines are provided with nitrogen valves. The sodium carbonate solution adding pipe, the hydrochloric acid solution feeding pipe and the first filtrate feeding pipe are respectively provided with metering pumps, and the sodium carbonate solution adding pipe and the hydrochloric acid solution feeding pipe are respectively connected with the sodium carbonate solution storage tank 20 and the hydrochloric acid solution storage tank 21.

[0035] The solid material of the second centrifuge 17 enters the purification kettle 4. A purification hydrochloric acid solution feeding pipe and a second filtrate feeding pipe are connected to the purification kettle 4. The discharge pipe of the purification kettle 4 is connected to the third centrifuge 22. The filtrate outlet of the third centrifuge 22 is connected to the second filtrate storage tank 23. The second filtrate storage tank 23 is connected to the second filtrate feeding pipe. Metering pumps are also provided on the purification hydrochloric acid solution feeding pipe and the second filtrate feeding pipe. The purification hydrochloric acid solution feeding pipe is connected to the purification hydrochloric acid solution storage tank 24.

[0036] The organic filtrate storage tank 15 is also connected to the inlet pipeline of the fractionating column 19 through a pipeline. The stabilizer outlet pipeline of the fractionating column 19 is connected to the stabilizer recovery storage tank 16. The methanol outlet pipeline of the fractionating column 19 is connected to the methanol recovery tank 6. The bottom residue outlet pipeline of the fractionating column 19 is connected to the incinerator 16. Valves are provided on all pipelines.

[0037] First, the prepared sodium methoxide methanol solution is placed in the sodium methoxide methanol solution storage tank 7 and pumped into the sodium methoxide methanol concentration kettle 1 by a metering pump. A heating jacket is provided outside the sodium methoxide methanol concentration kettle, which is the prior art. It is heated and concentrated, and methanol is distilled out. The distilled methanol vapor is condensed by a condenser pipe and collected into the methanol recovery tank 6. The concentrated sodium methoxide methanol solution is pressed into the reaction kettle 2 by nitrogen pressure, and then dimethyl malonate, formamide, and stabilizers (such as ethyl acetate, methyl formate, etc.) are pumped in by a metering pump. A catalyst (such as quaternary ammonium bases like tetramethylammonium hydroxide, tetramethylammonium bicarbonate, tetraethylammonium hydroxide, etc.) is added through the solid material inlet. A stirring device is provided in the reaction kettle, and it is heated for reaction. After the reaction is completed, it is cooled, and then methanol in the methanol recovery tank or the organic filtrate in the organic filtrate storage tank is added by a metering pump and stirred to disperse into a suspension. Then, hydrochloric acid methanol solution is added to the reaction kettle by a metering pump for acidification to slightly acidic, and the material is pressed into the first centrifuge by nitrogen for centrifugal filtration, and the organic filtrate is separated into the organic filtrate storage tank.

[0038] The solid mixture of 4,6-dihydroxypyrimidine disodium salt and sodium chloride is transferred into the crystallization kettle, washed with water through the water adding pipe, and then sodium carbonate solution is added by a metering pump until it is slightly alkaline to dissolve the solid, obtaining a mixed sodium salt solution.

[0039] Then, hydrochloric acid solution and the recycled first filtrate are added by a metering pump for acidification crystallization. The crystallization material is pressed into the second centrifuge by nitrogen for centrifugal filtration to obtain the crude product of 4,6-dihydroxypyrimidine. The filtrate of the second centrifuge enters the first filtrate storage tank for recycling.

[0040] The crude product of 4,6-dihydroxypyrimidine is put into the purification kettle, purified by adding purification hydrochloric acid solution or the recycled second filtrate, and then introduced into the third centrifuge by nitrogen for centrifugation. A water pipe is connected to the third centrifuge, and the solid is rinsed with water after centrifugation. After drying, the 4,6-dihydroxypyrimidine product is obtained.

[0041] The separated organic filtrate is recycled and used multiple times. When the formic acid content in the filtrate reaches a certain concentration, it is added to a fractionating column for fractional distillation to recover methanol and the stabilizer. The stabilizer is recycled. Methanol is collected in a methanol recovery tank. The bottom residue of the fractionating column enters an incinerator for incineration to burn the residual organic matter, obtaining a solid containing impurity sodium salt. The solid containing impurity sodium salt is dissolved with the primary filtrate, separated by filtration, the carbon residue is treated as waste residue, the filtrate is evaporated to recover water and recycled to the system for reuse, and sodium chloride by-product is obtained by evaporation and crystallization.

[0042] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A clean production system for 4,6-dihydroxypyrimidine, comprising a sodium methoxide methanol concentration kettle, a reaction kettle and a crystallization kettle, characterized in that: The sodium methoxide methanol concentration kettle is provided with a sodium methoxide methanol solution addition pipeline and a condenser, the outlet of the condenser is connected to the methanol recovery tank, the discharge pipeline of the sodium methoxide methanol concentration kettle is connected to the feed pipeline of the reactor, the reactor is also provided with a solid material addition port and a liquid material addition pipeline, a heating jacket is provided outside the reactor, the liquid material addition pipeline is divided into a plurality of branch pipes respectively connected to a dimethyl malonate feeding pipe, a formamide feeding pipe, a methanol feeding pipe, a stabilizer addition pipe, an organic filtrate feeding pipe and a hydrochloric acid methanol solution feeding pipe, the discharge pipeline of the reactor is connected to a first centrifuge, the filtrate pipeline of the first centrifuge is connected to an organic filtrate storage tank, the organic filtrate storage tank is connected to an organic filtrate feeding pipe, and the methanol recovery tank is connected to a methanol feeding pipe; The solid material of the first centrifuge enters the crystallization kettle, which is connected to a water adding pipe, a sodium carbonate solution adding pipe, a hydrochloric acid solution feeding pipe and a first filtrate feeding pipe, the discharge pipeline of the crystallization kettle is connected to the second centrifuge, the filtrate outlet pipeline of the second centrifuge is connected to the first filtrate storage tank, and the first filtrate storage tank is connected to the first filtrate feeding pipe; The solid material from the second centrifuge enters the purification kettle, which is connected to a feeding pipe for purified hydrochloric acid solution and a second filtrate feeding pipe. The discharge pipe of the purification kettle is connected to the third centrifuge, and the filtrate outlet of the third centrifuge is connected to the second filtrate storage tank, which is connected to the second filtrate feeding pipe.

2. The clean production system of 4,6-dihydroxypyrimidine according to claim 1, characterized in that: The sodium methoxide methanol solution adding pipeline is connected to the sodium methoxide methanol solution storage tank, and the sodium methoxide methanol concentrating kettle is connected to a nitrogen pipeline.

3. The clean production system of 4,6-dihydroxypyrimidine according to claim 1 or 2, characterized in that: The reactor is provided with a nitrogen pipeline, and the dimethyl malonate feeding pipe, formamide feeding pipe, methanol feeding pipe, stabilizer feeding pipe, organic filtrate feeding pipe and hydrochloric acid methanol solution feeding pipe are respectively provided with metering pumps, the dimethyl malonate feeding pipe and formamide feeding pipe are respectively connected to the dimethyl malonate storage tank and the formamide storage tank, the stabilizer adding pipe is connected to the stabilizer storage tank, and the hydrochloric acid methanol solution is connected to the hydrochloric acid methanol solution storage tank.

4. The clean production system of 4,6-dihydroxypyrimidine according to claim 3, characterized in that: The crystallization kettle and the purification kettle are also provided with nitrogen pipelines, and all nitrogen pipelines are provided with nitrogen valves. The sodium carbonate solution feeding pipe, the hydrochloric acid solution feeding pipe and the first filtrate feeding pipe are respectively provided with metering pumps, and the sodium carbonate solution feeding pipe and the hydrochloric acid solution feeding pipe are respectively connected to the sodium carbonate solution storage tank and the hydrochloric acid solution storage tank; The purified hydrochloric acid solution feeding pipe and the second filtrate feeding pipe are also provided with metering pumps, and the purified hydrochloric acid solution feeding pipe is connected to the purified hydrochloric acid solution storage tank.

5. The clean production system of 4,6-dihydroxypyrimidine according to claim 4, characterized in that: The organic filtrate storage tank is also connected to the inlet pipeline of the distillation tower through a pipeline, the stabilizer outlet pipeline of the distillation tower is connected to the stabilizer recovery storage tank, and the methanol outlet pipeline of the distillation tower is connected to the methanol recovery tank.

6. The clean production system of 4,6-dihydroxypyrimidine according to claim 5, characterized in that: The bottom residual liquid outlet pipeline of the fractionating tower is connected to the incinerator.

7. The clean production system of 4,6-dihydroxypyrimidine according to claim 1, characterized in that: A stirring device is arranged in the reactor.

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